Earlier this month the well owners who participated in the
2026 Prince William County Well Water Clinic received their results by email.
Below you can see the summary of what was found in the 70-water analyses
performed (this was the smallest group in several years). VA Tech tested for
the naturally occurring contaminants and common sources of contamination: a
poorly sealed well or a nearby leaking septic system, or indications of
plumbing system corrosion. These are the most common contaminants that affect
our drinking water wells. Also, this year they expanded their analysis to
additional metal contaminants from plumbing sources and additional contaminants
with health concerns.
To determine if treatment is necessary, water test results
should be compared to a standard-usually the U.S.EPA Safe Drinking Water Act
(SDW) limits. Though private wells are not regulated by the U.S. Environmental
Protection Agency (EPA) or the Safe Drinking Water Act, the SDW act has primary
and secondary drinking water standards that we use for comparison. Primary
standards are ones that can impact health and from the tested substances
include coliform bacteria, E. coli bacteria, nitrate, lead, and arsenic.
Secondary standards impact taste or the perceived quality of the water. Then
there are the substances with a health reference level (HAL) below which health
impacts are not anticipated and LHA a level of contamination that if consumed
over a lifetime may have health impacts.
Just because your water appears clear does not mean it is
safe to drink. The 2026 Prince William County water clinic found that 25.7% of
the wells tested PRESENT for coliform bacteria. This is higher than last year.
Coliform bacteria are not a health threat itself; it is used to indicate other
bacteria that may be present and identify that a well is not properly sealed
from surface bacteria. The federal standard for coliform bacteria is zero, but
the federal standard allows that up to 5% of samples can test positive for
coliform during a month.
Three of the 18 bacteria contaminated wells tested positive
for E coli. Fecal coliform and E. coli are bacteria whose presence indicates
that the water is contaminated with human or animal wastes. Disease-causing
microbes (pathogens) in these wastes can cause diarrhea, cramps, nausea,
headaches, or other symptoms. These pathogens may pose a special health risk
for infants, young children, and those with compromised immune systems.
However, people can drink water contaminated with fecal bacteria and not
notice.
If your well is contaminated with coliform but not fecal coliform or E. coli,
then you have a nuisance bacteria problem, and the source may be infiltration
from the surface from rain or snow melt. Typical causes are improperly sealed
well cap, well repairs performed without disinfecting or adequately
disinfecting the well, failed grouting or surface drainage to the well. Very
low levels of coliform (1-5 MPN) may appear in an older well during extremely
wet springs.
If your well was found to have coliform bacteria present you
should shock chlorinate the well (according to the procedure from VA Tech),
repack the soil around the well pipe to flow away from the well and replace the
well cap. Then after at least two weeks and the next big rainstorm retest the
well for coliform. If coliform bacteria is still present then a long-term
treatment should be implemented: using UV light, ozonation, or chlorine for
continuous disinfection. These systems can cost up to $2,000 installed (maybe
more with recent price increases).
If you have fecal coliform in the well or E. coli, your well
is being impacted by human or animal waste, and you are drinking diluted
sewage. This year 4.3% of the wells tested were found to have E. coli present.
If there is not a nearby animal waste composting facility, then you are
probably drinking water from a failed septic system- yours or your nearest
neighbors or in some areas a leaking sewer line. To solve this problem, you
need to fix or replace the septic system that is causing contamination, replace
the well or install a disinfection and micro filtration or reverse osmosis
system. Giardia or Cryptosporidium are two microscopic parasites that can be
found in groundwater that has been impacted by surface water or sewage. Both
parasites produce cysts that cause illness and sometimes death. Chlorine can
work against Giardia but not Cryptosporidium. Ultraviolet (UV) light works
against both Giardia and Cryptosporidium so it is the preferred method of
treating this problem.
The failing septic systems can often be identified by using tracer dyes. While
continuous disinfection will work to protect you from fecal bacteria and E.
coli, be aware that if your well is being impacted by a septic system, then the
well water might also have present traces of all the chemicals and substances
that get poured down the drain. Long term treatment for disinfection and
micro-filtration should be implemented: using UV light, ozonation, or chlorine
for continuous disinfection, carbon filtration, and anything that is used for
drinking should be further treated with a reverse osmosis systems or micro
membrane system both work by using pressure to force water through a
semi-permeable membrane. Large quantities of wastewater are produced by reverse
osmosis systems and need to bypass the septic system, or they will overwhelm
that system creating more groundwater problems. Reverse osmosis systems produce
water very slowly, a pressurized storage tank and special faucet need to be
installed so that water is available to meet the demand for drinking and
cooking.
Nitrate can contaminate well water from fertilizer use; leaking from septic
tanks, sewage and erosion of natural deposits. None of the wells in our group
of 70 samples had nitrate levels above the MCL. The average level of nitrates
was under 2 mg/L. The regulatory limit for nitrate in public drinking water
supplies, 10 mg/L, was set to protect against infant methemoglobinemia, but
other health effects were not considered and are emerging as problems. Nitrate
in a well tends to climb slowly over the years if the septic systems do not
have at least 3 acres between them. Based on a study done years ago in Dutchess
County NY at least 3 acres are necessary to naturally treat the nitrate.
Dr. Mary Ward of the Occupational and Environmental Epidemiology Branch,
Division of Cancer Epidemiology and Genetics, National Cancer Institute has lead
several important studies comparing all the research on the health impacts from
exposure to nitrate in water. The first review was of studies published before
2005. In 2018 Dr. Ward was lead author on a review of more than 30
epidemiologic studies on drinking water nitrate and health outcomes. If
your nitrate-N levels are climbing, you might want to read Dr. Ward’s work.
There are AOSS systems designed to remove nitrate. These are very expensive
(think new car expensive.)
This year they found 2 of homes had first draw lead levels above the SDWA
maximum contaminant level of 0.01 Mg/L. After flushing the tap for at least one
minute none of the homes had lead levels above the 0.1 mg/L level; however,
many scientists do not believe that any level of lead is safe to drink over an
extended period of time. Often homes that have elevated lead in the first draw,
have lower pH values. Corrosive water is the primary risk for lead in well
water. However, over time water with a neutral pH could dissolve the coating on
galvanized iron, in brass well components and plumbing fixtures.
Houses built before 1988 when the ban on lead went into
effect and have low pH water typically have higher lead concentrations. Lead
leaches into water primarily as a result of corrosion of plumbing and
components in the well itself but can also result from flaking of scale from
brass fittings and well components. Corrosion control techniques such as
adjusting pH or alkalinity that are commonly used to neutralize aggressive
water will not work in to reduce lead being leached from well components. For
most instances, though, a neutralizing filter and lead removing activated
carbon filters can be used to remove lead leaching from plumbing pipes, solder
and fixtures. Recently, some home water treatment companies are offering home
treatment systems that neutralize the water and add orthophosphate other
phosphate solution to coat the piping to prevent further corrosion of metal
pipes. It should work if maintained. This type of solution is used in public
water supplies. I have no experience with this type of home system and am not
aware of any testing.
Iron and manganese are naturally occurring elements commonly
found in groundwater in this part of the country. Seven of the wells tested
exceed the iron standard and 5 exceeded the manganese standard. At naturally
occurring levels iron and manganese do not present a health hazard. However,
their presence in well water can cause unpleasant taste, staining and
accumulation of mineral solids that can clog water treatment equipment and
plumbing and discolored water. The standard Secondary Maximum Contaminant Level
(SMCL) for iron is 0.3 milligrams per liter (mg/L or ppm) and 0.05 mg/L for
manganese. This level of iron and manganese can be detected by taste, smell, or
appearance. In addition, some types of bacteria react with soluble forms of
iron and manganese and form persistent bacterial contamination in a well, water
system and any treatment systems. These organisms change the iron and manganese
from a soluble form into a less black or reddish brown gelatinous material
(slime). Masses of this slime, iron, and/or manganese can clog plumbing and
water treatment equipment even in extreme circumstances clog up a well pump.
All systems of removing iron and manganese essentially involve oxidation of the
soluble form or killing and removal of the iron bacteria. When the total
combined iron and manganese concentration is less than 15 mg/l, an oxidizing
filter is the recommended solution. (Iron bacteria, hydrogen sulfide and
tannins can also be removed with pre-chlorination.) An oxidizing filter
supplies oxygen to convert ferrous iron into a solid form which can be filtered
out of the water. Higher concentrations of iron and manganese can be treated
with an aeration and filtration system. This system is not effective on water
with iron/ manganese bacteria but is very effective on soluble iron and
manganese, so you need to do further testing to determine what type of
iron/manganese you have before you install a treatment system. Newer iron
filters have an option to add an ozone generator to kill reducing bacteria. Water
softeners can remove low levels of iron and manganese and are widely sold for
this purpose because they are very profitable but are now being banned in some
locations due to rising sodium and chloride levels, what is known as inland salinization.
Increasing salinization of our water resources is a growing problem in our
region. Also, water softeners are easily clogged by iron bacteria.
Chemical oxidation can be used to remove high levels of dissolved or oxidized
iron and manganese as well as treat the presence of iron/manganese (or even
sulfur) bacteria. The system consists of a small pump that puts an oxidizing
agent into the water before the pressure tank. The water will need about 20
minutes for oxidation to take place so treating before a holding tank or
pressure tank is a must. After the solid particles have formed the water is
filtered. The best oxidizing agents are chlorine or hydrogen peroxide. If
chlorine is used, an activated carbon filter is often used to finish the water
and remove the chlorine taste. The holding tank or pressure tank will have to
be cleaned regularly to remove any settled particles.
The pH of water is a measure of the acidity or alkalinity. The pH is a
logarithmic scale from 0 – 14 with 1 being very acidic and 14 very alkaline.
Drinking water should be between 6.5 and 8.5. For reference and to put this
into perspective, coffee has a pH of around 5 and salt water has a pH of around
9. Corrosive water, sometimes also called aggressive water is typically water
with a low pH. (Alkaline water can also be corrosive.) Low pH water can corrode
metal plumbing fixtures causing lead and copper to leach into the water and
causing pitting and leaks in the plumbing system. The presence of lead or
copper in water is most commonly leaching from the plumbing system or well
rather than the groundwater. Acidic water is easily treated using an acid
neutralizing filter. Typically, these neutralizing filters use a granular
marble, calcium carbonate or lime. If the water is very acidic a mixing tank
using soda ash, sodium carbonate or sodium hydroxide can be used. The acid
neutralizing filters will increase the hardness of the water because of the
addition of calcium carbonate. 17.1% of the wells tested were found to have
acidic water and 2.9% were found to have a high pH (probably from too much salt
in the water softener) this year. A too high a pH is usually from over treating
with a water softener, but can be an expression of salt water infiltration or other
pollution.
Water that contains high levels of dissolved minerals is commonly referred to
as hard. Groundwater very slowly wears away at the rocks and minerals picking
up small amounts of calcium and magnesium ions. Water containing approximately
120 mg/L can begin to have a noticeable impact and is considered hard.
Concentrations above 180 mg/L are considered very hard. Hard water can be just
a minor annoyance with spotting and the buildup of lime scale, but once water
reaches the very hard level 180 mg/L or 10.5 grains per gallon, it can become
problematic. Overall, 7.1% of homes tested had very hard water. (It is to be
noted about half of homes reported having a water softener.)
Two methods are commercially available (and certified) to
treat hard water. A water softener and a water system that work through a
process called template assisted crystallization (TAC), have been certified by
DVGW-W512 and are available in whole house units. In template assisted
crystallization, water flows through a tank of TAC
media. When the hard water comes into contact with the media, the magnesium
and calcium ions are caught by the nucleation sites. As more calcium and
magnesium ions build up within the sites, small micro-crystals form and flow
through your plumbing. They do not attach themselves to your water pipes as
scale.
The ubiquitous water softening system is an ion exchange system consisting of a mineral tank and a brine tank. The mineral tank holds small beads of resin that have a negative electrical charge. The calcium and magnesium ions (along with small amounts of other minerals) are positively charged and are attracted to the negatively charged beads. This attraction makes the minerals stick to the beads as the hard water passes through the mineral tank. Sodium from salt is used to charge the resin beads. The brine tank is flushed out when the resin beads are recharged carrying the salty solution to the environment. Inland salinization of surface waters and groundwater is an emerging environmental concern. Research has shown that salinization has affected over a third of the drainage area of the contiguous United States even in areas without road salt. At the present time the EPA guidance level for sodium in drinking water is 20 mg/L. Given the number of homes with elevated sodium and our local geology, it is probably a reflection of the number of homes with water softeners-45.7% of the wells tested had elevated sodium.Elevated uranium was found in one sample. Because uranium gets into your body primarily through ingestion (and not through the skin or through inhalation), it is not usually necessary to treat all the water in your home, but only the water you drink. Reverse osmosis (RO) treatment systems are the most common type of treatment used for uranium removal and are very effective.
Traces of other metals were found in a small handful of
samples. Activated carbon filters are used to address these problems. When the
activated carbon is fully contacted with water, the heavy metal ions will be
adsorbed into the developed voids of the activated carbon to remove the
contaminant.
